Age undoubtedly plays a large role in the efficiency of a professional athlete. As the years slowly creep up, Father time takes its hold and never lets go. However, in the game of baseball, we’re still seeing grey-haired players light up scoreboards with their impressive strokes. Arguably, it may not be as physically-demanding as soccer or football, but it’s still a tried-and-true game that requires the very best out of an athlete.

It never ceases to amaze me when I see guys like Ichiro Suzuki and David Ortiz continue to take the field. The fact that they’re in their “grizzled” age and are still producing runs just polishes their already established legacy. It’s an incredible feat, no doubt about that. And, it doesn’t hurt that the grossly enormous amounts of money that they’re being paid allows them to live whatever lifestyle that they please. But, that’s just secondary, right?

In this list, I’ll cover the MLB’s oldest players that are still valiantly serving their teams. Surprisingly, but not so surprisingly, many of these players still provide a spark to their team and continue to be relied on – as evidenced by their contracts. But, baseball’s always been a sport that’s been filled with older players. Most recently, veteran pitcher Jamie Moyer retired in 2012 at the age of 49 – in which he was the oldest pitcher in the history of the MLB to record a win. And then you have Satchel Paige, who played until the elderly age of 59. Baseball remains a sport that continues to showcase the incredible willpower and physical strength of these ageless athletes. They say age is just a number. In the game of baseball, it truly is.

15 Adrian Beltre (Apr. 7, 1979)

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The 37-year-old Silver Slugger made waves in the league when he was first scouted by the Los Angeles Dodgers when he was at the tender age of 15. His MLB debut came in 1998, when he started at third base against the Angels. Since then, Beltre never looked back, garnering multiple Gold Glove and Silver Slugger awards with four All-Star appearances – while creating a signature one-knee home run swing in the process. Beltre remains a leader on a youthful Texas Rangers team, and looks primed to continue playing into his twilight years. But, just don’t pat him on the head for that.

14 John Lackey (Oct. 23, 1978)

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Lately, the resilient pitcher has proven that his velocity and command are still there. Last season with the Cardinals, Lackey pitched 218 innings with a 2.77 ERA and 175 strikeouts. That’s not too bad for 37 years of age – not to mention he made 33 starts as well. That’s more than enough proof that he’s earned his worth. Lackey would then go on to sign with the Chicago Cubs – where he’s currently at - in the hopes that he can still obtain a ring in his later years. And, Chicago has all the pieces in place to get him one too.

13 David Ross (Mar. 19, 1977)

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Chicago Cubs catcher David Ross has earned the respect of nearly every team that he’s played on, both as a mentor and a leader. It was also announced that this would be Ross’s final year in the Major Leagues. Known for being a power hitter his entire career, Ross has definitely take a step backwards in terms of power – as evidenced by his .176 BA last year. However, don’t overlook the 39-year-old. Ross has been known for his unique ability to handle pitchers and his final year on the field may lead to a storybook ending for the journeyman.

12 Carlos Beltran (Apr. 24, 1977)

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Beltran has been one of the most efficient in the entire league at stolen bases, amassing an 86% success rate. And, not only that, but he’s also been absolutely clutch during playoff time, with nine postseason home runs. Although he’s lost a step over the last few years, Beltran still has that reserve in the tank left for when the Yankees are going to need it. A three-time Gold Glove Award winner and two-time Silver Slugger, Beltran’s on pace to set himself up for an appearance in the Hall of Fame – and maybe one last go at a World Series win.

11 Buddy Carlyle (Dec. 21, 1977)

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The journeyman reliever may not be a household name, but he’s been in the league since 1999 despite a relatively rough career. Carlyle bounced back and forth from overseas to the States multiple times in his career. In addition, Carlyle’s major league stints were extremely limited, sometimes pitching only a few games before getting sent back down to the minors. He arguably had the best season of his career on the New York Mets during the 2014 season where he posted a 1.45 ERA in 27 games. He may not have had the most illustrious career, but you can’t help but marvel at the dedication the guy has to the sport.

10 Joel Peralta (Mar. 23, 1976)

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The 40-year-old right-handed relief pitcher had stints on seven teams over the span of his career. Initially, Peralta started out as an outfielder in the Dominican Summer league for the Oakland Athletics. It wasn’t until he signed with the Anaheim Angels that he converted to a relief pitcher. He currently stands at a 19-34 win-loss record with 579 strikeouts and is signed to a minor league contract for the Seattle Mariners. This may very well be his last stop in the league before deciding to call it quits – he was almost sent to retirement after dealing with nerve issues in his right triceps when he played for the Dodgers last year.

9 Matt Thornton (Sept. 15, 1976)

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Drafted in the 1995 Major League Baseball Draft, Thornton started his baseball career with the Seattle Mariners as a reliever. After two sub-par seasons, Thornton was then traded to the Chicago White Sox where he began showing significant signs of improvement. With proper tutelage, Thornton became a dominating force in the Sox bullpen, making the All-Star team in 2010 (his first All-Star selection of his entire career). The 39-year-old recently signed a minor league deal with the San Diego Padres and is still looking for a chance to prove that he can still deliver a mean four-seamer.

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8 Jason Grilli (Nov. 11, 1976)

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The 39-year-old reliever for the Atlanta Braves made a buzz when he returned from a ruptured Achilles tendon last year and consistently pumped out 93-mph fastballs in training camp. Although the years are catching up to him, Grilli continues to be a role player in the rotation, and hopes to pick up where he left off prior to the season-ending injury when he was pitching an ERA of 2.94. Depending on his performance this season, we may very well be witnessing Grilli’s final season in a Braves uniform. It’s a make-or-break year for the “Grilled Cheese” Grilli.

7 A.J. Pierzynski (Dec. 30, 1976)

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Known for his colorful and strong demeanor, the journeyman catcher wasn’t one to shy away from being high maintenance. In 2012, he was voted the most hated player in the league. He even thanked his teammates for putting up with him during the White Sox victory parade. Attitude aside, the 39-year-old is still a reliable and consistent batting option. And, he’s only one hit away from joining an exclusive backstop club that few see the likes of. Pierzynski will become only the 10th catcher to amass 2,000 hits in his career (led by Ivan Rodriguez).

6 Koji Uehara (Apr. 3, 1975)

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A trusty reliever for the Red Sox, the 41-year-old pitcher still remains a force to be reckoned with – assuming he’s healthy. With a reliable splitter, Uehara is still dominating the game much to the amusement of his teammates. However, Boston has been actively trying to lighten his workload and has even given him the role of playing the eighth as a closer over the relief position. Although it isn’t an unfamiliar role as Uehara started with the team as a seventh- and eighth-inning guy, it’s still a decision that’s puzzled many. But, at the ripe age of 41, adjustments must be made in order to keep their dominant reliever healthy.

5 Alex Rodriguez (July 27, 1975)

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Despite putting up stellar seasons that very few could match, the PED controversy still looms over the 40-year-old like it was yesterday. The once-beloved player has become the villain of baseball. But, allegations aside, Rodriguez still brings his “A-game” every time he steps on the field. Last year, he knocked out 33 homers (which was the most he had since 2009) and finished out the season in a dominant fashion. The question is whether or not he can bring the Yankees back into postseason relevance. He still remains a bright spot on a somewhat power-starved offense.

4 David Ortiz (Nov. 18 1975)

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It’s strange to know that after this season, we’re losing Big Papi to the world of retirement. Although he wholeheartedly deserves it, it almost seems like the game is losing a pivotal figure that made baseball more exciting – especially for Boston fans. In terms of production, the 40-year-old isn’t exactly playing like his age. Last season, Ortiz racked up 37 home runs and 108 RBIs while amassing a .273 batting average. That’s a pretty impressive feat when you think about it. Will he be able to replicate his past success in his final year? I’m really intrigued to find out.

3 R.A. Dickey (Oct. 29, 1974)

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The former Cy Young Award winner still has a mean knuckleball that’ll catch batters if they’re not careful. Although he’s far from being the ace player that he used to be, he’s proven that he can still be dependable (even after recent sub-par near .500 seasons). Furthermore, Dickey still has the drive and love for the game and is seeking a redemptive year. He’s yet to announce anything about retirement, so we baseball fans get to enjoy him for at least another couple years. Now, the only question is how much left he has in the tank.

2 Ichiro Suzuki (Oct. 22, 1973)

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The 42-year-old Japanese sensation has entertained the league for years with his consistent hitting and defense. Although the years haven’t been too kind for Ichiro, who’s been hitting league-average at best, he still has one goal that he can look forward to this season – the 3000 club. As stated in interviews, Ichiro plans to play beyond 2016 to attain the coveted title, and another ring. He’s even been caught on the record saying that he could play until 50. While that may be a far reach, one goal isn’t. It seems like all eyes are currently on him to reach that 3,000 mark.

1 Bartolo Colon (May 24, 1973)

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Bartolo Colon is the oldest active player in the major league. “Big Sexy” as he’s known by his teammates, is still delivering his trademark fastball. And, while it’s not topping 100 miles per hours anymore, he still remains an arguably productive option in the rotation. His most recent memorable moment came after he was caught in a 50-game PED suspension in 2012. The following year he bounced back, going 18-6 with 3 shutouts and a 2.65 era. Now, we may never see Colon launch Aroldis Chapman-like fastballs anymore, but we do have the guilty pleasure of watching his perfect swing.